Luke Do was a lively 18-month-old awaiting the birth of his first sibling when he was diagnosed with a rare form of leukemia.

The hopes of his parents, both doctors in San Jose, Calif., immediately turned to a bone marrow transplant, but they soon learned some distressing news — Luke’s ethnic heritage made him a tough match.

Sarah Gaskins, Luke’s mother, has Japanese and European ancestors and his father, Lam Do, is Vietnamese-American. Because bone marrow matches usually are made with a relative or someone with the same racial or ethnic background as the patient, multiracial people rarely have success.

“It’s tragic,” said Lam Do, who specializes in internal medicine. “Your chance of finding a donor is so low, it’s like winning the lottery. And most people are unaware of this.”

Limited donors

For years, the medical community has pushed for increased donor registry among racial minorities to improve survival rates for leukemia, lymphoma and other blood diseases. But to the general public, the situation is little known.

Only 2 percent of those who list their ancestry with the National Marrow Donor Program are multiracial, though the NMDP will — for the first time — study multiracial patients’ medical records this year to better understand what kind of marrow tissue they tend to inherit from their parents. The group also will try to more effectively recruit new potential donors, said Helen Ng, an NMDP spokeswoman.

“Using the patient information we have access to, we’re trying to understand a little better the issues they face,” said Ng, whose group, with 5.6 million potential donors registered, has the largest such list in the world.

Matt Kelley, president of Mavin Foundation, a Seattle-based advocacy group for multiracial people, says the inattention to the problem reflects society’s reluctance to accept today’s increasingly complex racial landscape.

Sarah Gaskins, left, Lam Do, and Luke Do, 4, center, look at a photo of Luke together with his bone marrow donor, Randall Yamanaka, at their home in San Jose, Calif.

“It’s a headache,” said Kelley, whose group has an ongoing bone marrow program. “The reality is that many organizations are afraid of addressing race period — they don’t feel competent or comfortable — and when it comes to addressing mixed heritage issues, they don’t want to go there, either.”

Tough match

Today, whites in need of a bone marrow transplant have about a 90 percent chance of finding a match, said Dr. Patrick Beatty, an oncologist with the Montana Cancer Specialists in Missoula, Mont., who researches ancestry and bone marrow. For those who aren’t white, “your chances of getting a match are pretty remote,” he said.

The biological reason has to do with the body’s response to infections, Beatty said. Because the world’s ancient peoples were exposed to different diseases over millennia, each group developed different tissue antigens, substances that help fight illness.

The descendants of these peoples retain those highly varied tissue antigens, he said, making it tough to match the bone marrow of individuals from different ancestries.

Looking for happy endings

Luke Do’s family was elated when, about six months after his diagnosis, they learned a marrow match had been found for the boy with a Japanese-American police officer in Seattle.

Luke struggled for months after the transfusion, nearly dying three times, but hung on in the end. Now the Dos are making plans for him to start kindergarten in the fall — and to celebrate the third anniversary of his transplant on March 18.

The Rivera family of Los Altos, Calif., is still hoping for a similar happy ending.

Chris Rivera, 24, has fought leukemia with chemotherapy for six years. Chris, who also has Down Syndrome, thrived until last October when he was diagnosed with a more lethal form of the blood cancer. He desperately needs a bone marrow transplant within the next year, according to his mother, Kathy Rivera.

“It’s so sad, but he’s not a very good candidate for a match and it has nothing to do with the fact that he has Down Syndrome,” she said. “It’s because my husband is Puerto Rican and I’m of northern European heritage.”

Like many others, the family is scouring the community, posting Internet messages and praying that a match will be found. They regularly help organize bone marrow registry drives, hoping one will beat the odds and turn up the right tissue.

Much of this activity is taking place in Northern California, home to half of the 10 U.S. cities with the highest percentages of multiracial individuals, according to Census 2000. The cities include Hayward, Stockton and Daly City.

Millions of mixes

Nationwide, Census data counted about 7 million people of multiracial heritage — the first time an option was available to check more than one racial category. Mavin organizers estimate that number is closer to 10 million.

Within that group, there are millions of possible ethnic mixes, and therefore millions of potential challenges for someone seeking a bone marrow match. Complicating the situation further, research shows that minorities have greater tissue variation than whites. Africans and their descendants globally have the most variation of any population in the world, “many, many more tissue types than Caucasians,” Beatty said.

“Many (multiracial) people have very little contact with entities that recognize them correctly,” said Kelley of Mavin, adding that this typically results in hurt feelings and a sense of social isolation. “We don’t have that luxury when it comes to people’s health.”